Wednesday, January 2, 2019

Happy New Year! A Cone 9 - 10 dolomite matte glaze for you to try!

I think that Santa and his cat must have gone fishing this Christmas, and the postcard that he sent me is evidence of this! The great day came and went in rather a rush and left us a bit surprised that it had been there at all. Laura and I were fairly tired in the run up to Christmas, so we had a quiet day at home, just the two of us... well, 4 really when we include the cats!

I did try to get this card finished and sent away on Christmas Day, but it didn't quite happen, so here it is now as a Christmas/New Year thing.

At this time of year it is usual for people to drop in! We were delighted to meet up with Gwynneth and Vic (The Pirate) who I have read about for several years now on "Ook?!" Gwynneth's blog. Gwynneth is a very experienced and accomplished potter and does lovely linocuts as well, and Vic is a retired aircraft engineer. They are currently in New Zealand intending to compete in cycling events at the Masters Games and were able to travel far enough South this time to come and see us.

It is lovely to meet other bloggers "in the round" as it were, and we made sure that we remained comfortably three dimensional by having an evening out with them and feasting together on yummy wood fired pizzas at "Salt and Sugar" the Karitane General Store in the next village!

Gwynneth, Laura and Vic
 Vic is 20 years my senior, and was able to confirm what the weather was like in the village of Rye where I was born on the day of my birth! Vic was taking part in a cycling event near Rye in the UK on that Blessed Day, and attests to the fact that the weather was just as appalling as it is in my mother's account of things! ("It was a dark and stormy night, my son, and the Midwife could not get to you in time....., etc"). Vic has a photo of another competitor sheltering under a cape as the rain pours down. What fun!

Meeting such lovely people is a happy/sad thing as there is always so much to talk about, and never enough time, but we are really thankful for the hours we had and for the enduring warmth of friendship.

Christmas, and the week or so after it, is an odd tumble of days which quickly lose their comfortable labels of Monday, Tuesday, Wednesday and the like, and today, which my calendar informs me is a Tuesday, really feels like Saturday because it is New Year. In spite of the uncertainty, I have managed to get a glaze firing through the electric kiln and should have some new bowls to put out in our little gallery tomorrow, all going well!

Recently I was pleased to rediscover one of my gazes that I had developed in 2014, a dolomite matte glaze that was intended to be a useful substitute for an old faithful glaze that I had used before when I could still get Cornish Stone at a sensible price... and "proper" Cornish Stone, not the less interesting substitute that you get these days. Real Cornish Stone from Cornwall UK was a fascinating material. A complete high temperature glaze in itself, this natural material contained the glass former silica, the stabilizer alumina, and fluxes sodium, potassium and calcium, with the interesting addition of a trace of Fluorine (if you were lucky!). Quite a nice high temperature clear glaze could be made from it by adding just a little more flux, such as 8 - 12 percent calcium carbonate.

By studying the chemistry of the various natural materials we use for potting it is possible to make reasonable substitutes in some cases, but they are never really the same as the natural ones, that doesn't mean that they are necessarily inferior, just different, rather like family members that look much the same, but have unique personalities!

At the time that I made the glaze, I did not do a great deal with it other than use it on a few test pieces, and 2 liters sat for 4 years in a bottle, not coming to any harm as such, but looking rather neglected! At the time I probably found the glaze OK, but not hugely inspiring on the rather iron rich stoneware clay I was using. Now I am using a porcelain body I am really delighted with the result.

Here is my Dolomite Matte recipe. This is a cone 9 - 10 glaze and I have only tried it thus far in oxidation, but suspect it will perform OK in reduction too. Best on porcelain or white stoneware. Stores well!!

Soda Feldspar    25
China Clay          25
Silica                   20
Dolomite             15
Potash Feldspar  10
Whiting                 5
Talc                       3

Total = 103



I tried the glaze on some rice bowls that I had "thrown off the hump", and I improvised some fish with brush decoration in cobalt and red iron oxide. The little bowls really feel and look just right so I am very pleased.



Happy New Year to you all!

11 comments:

Anna said...

How great to have that connection with Gwyneth and her husband... I love meeting up with other pottery bloggers too... I do follow Ook so will watch to see what she says about her travels.
Love the fishes.
Happy New Year to you and Laura

Peter said...

Happy New Year Anna,
It certainly is fun to meet with bloggers in addition to the exchange of comments and messages, we have some lovely memories to treasure of such times.
We are actually having the occasional warm summer day here now where we get almost to 30 degrees outside. I am enjoying the relative coolness of our old building on those days, it really is nice in my studio then where we probably reach the low 20s. I suspect those are more like winter temperatures for you!!! :-)

charlie said...

hi Peter .Glad to see you are posting again and potting as well! Very nice brushwork on the fish.Love them.Kind regards Charlie Seakins in Auckland

Peter said...

Hi Charlie,
Lovely to hear from you all the way from sunny Auckland! Thank you so much for your encouragement. More bowls are drying on my drying shelves as I write. I am enjoying the brush decoration, something I haven't done much of for a long time, and it is really good fun improvising fish designs.

PP said...

Happy New Year Peter - nice to find a new post on the blog.

It's lovely when blog contacts turn into meetings with actual people. I used to write a blog about the house we restored in Sydney and made a couple of good friends from doing that.

The bowls are lovely and I thought I'd give the glaze a go (I've just made up a quantity of the de Boos flecky green). Could I ask whether the dolomite matte is translucent or opaque (a glazer could tell from the ingredients, but I'm not a glazer!) and whether you think colours could be added to it, either stains or the usual coppers etc?

Whilst browsing glazy the other day I saw several of your recipes there, all fully attributed to you. Nice to see them getting around.

Peter said...

Happy New Year PP,

It certainly is nice to meet actual people, the internet can make the world a more friendly place after all!!

Do give the dolomite matte a go. You will probably find the glaze almost opaque, but not completely so. It does not have opacifiers such as zircon, or tin oxide, but the nature of a matte glaze like this is to be composed of thousands of tiny crystals which effectively scatter the light and make it look "solid" rather than glassy and clear.

I have not experimented with adding colours to this glaze as yet, because I haven't used it a great deal, but it will probably respond in a similar way to other matte glazes that have magnesium and calcium. As it is a matte glaze it would be best to aim for pastel shades rather than strong colours.

These are all guesses, but.... Cobalt blue will probably give a slightly violet shade of blue. On its own chromium oxide would very likely give brown, but could be used in small amounts of about 0.5 percent to modify copper or cobalt. I suspect that 1 - 2 percent iron oxide may give more of a pale yellow-brown, and 1 - 2 percent copper carbonate a pale, but slightly dull, green.

Do try it and let me know how you get on! :-)

I do like what glazy.org are doing, it is a most useful site, and... I must start to put some glazes up there myself. It is nice to see some of mine there already.

Best Wishes,

Peter

Linda Starr said...

happy new year to you and Laura, those are some sweet bowls and nice to see a blogging friend in person.

Anonymous said...

Hi Peter, I shall fire a test of your glaze in my cone 10 reduction fire in early February if all goes well, and will let you know how it turns out for me. I’ve followed Gwyneth’s blog over the years and great to see that she and the pirate made landfall in your part of the world. Lovely brushwork on your bowls! Cheers from Oregon, Owen

Peter said...

Happy New Year Linda,
Very nice to hear from you. Thank you for the encouragement you have been to me over the years, the blog has been a great way of "traveling" from one side of the world of the other even though it has mostly been through words and pictures!
Kind Thoughts to you and Gary,
Peter & Laura

Hi Owen,
Good to year from you. It would be wonderful help if you could do a test of the matte glaze in reduction, it will be very interesting to see how it turns out. I would expect a slight satin sheen in reduction, and it might give a grey celadon over an iron bearing clay. I have been glazing some more bowls with the same glaze this afternoon for a firing in the electric kiln. All going well, I will find the time to do the brush decoration tomorrow.
Happy New Year to you,
Peter

PP said...

Hi again Peter

Thank you for you reply. I'll give the new glaze a go, and experiment with a few colours and I will indeed let you know how I go.

I tried yesterday to post a photo here of some test mugs I made with your green/blue flecky, but had no luck. When I figure out how to do it, I'll have another bash. You said in a previous post that you only need a couple of good glazes, and I think this one will be one of mine (especially since I mostly make unglazed non-functional stuff). It has such a lot of movement and interest - the almost violet speckles running through it are lovely. It's actually the first glaze I've made that I've really liked, and I can now see why people get hooked on the whole voyage of discovery with glazes. Thank you once again so much for your generosity. I know I'm not the only one who appreciates it.

Peter said...

Hi PP,
Thank you for the lovey comment, I'm glad that you are enjoying the green/blue glaze. It would be great to see some photos, but I don't think it is possible to send such things via the comments section of the blog. You are most welcome to email me and send them that way. You should be able to track my email address down in the Contact page of this blog.

Do let me know how you get on with the matte glaze and with any colours you try, it will be very interesting and helpful to see how it works on other clay bodies and with glaze materials from different parts of the world.

Best Wishes,

Peter